System and method of controlling electric motors.



1. LE C. DAVIS,

1 1 99,45 3 Patented Sept. 26, 1916. I 3 SHEETS-SHEET I.

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. 28 i 1 i i I l I l-l I K 3 31 WITNESSES: INIEIITOII %744 Qua B J. LEC. DAVIS. SYSTENI AND METHOD OF CONTROLLING ELECTRIC MOTORS.

APPLICATION FILED NOV. 8. 1911.

Patented Sept. 26, 1916.

3 SHEETS-SHEET 2.

I WITNESSES: INVENTOH I i MAM I ATTORNEY.

J. LE C. DAVIS. SYSTEM AND METHOD OF CONTROLLING ELECTRIC MOTORS.

APPLICATION FILED NOV. 8, 19H- 1,199,4;53, PatentedSept. 26,1916.

3 SHEETS-SHEET 3- j A Z m 72.

WITNESSES: Egn

" UNITED STATES PATENT orrron.

JOSEPH LE CONTE DAVIS, OF PITTSBURGH, PENNSYLVANIA, ASSIGNOB T WESTING-HOUSE ELECTRIC AND MANUFACTURING COMPANY, A CORPORATION OE TENNSYL-VANIA.

SYSTEM AND METHOD OF CONTROLLING ELECTRIC MOTORS.

Specification of Letters Patent.

Patented Sept. 26, 19%.

Lpplication filed. November 8, 1911. Serial No. 659,158.

To all whom it mag concern:

Be it known that I, JOSEPH Ln C. 'DAVIs, a citizen of the United States,and a resident of Pittsburgh, in the county of Alle-. gheny and State ofPennsylvania, have in-' vented a new and useful Improvement in Systemsand Methods of Controlling Electric Motors, of which the following is aplied with energy from storage batteries.

3 The object of my invention is to provide 'a simple method ofcontrolling electric mo tors of the class above indicated and a systemembodying the same, by means of which a plurality of motor-operatingspeeds may be secured without changing the circuit connections of thebattery, without the material loss of energy in external resistance orresistances, and without either interrupting the motor circuit ormaterially reducing the torque of the motor in passing from any controlposition to the next.

Various methods of controlling vehicle motors have heretofore beendevised, among which I desire to call attention to the following: PatentNo. 765,209, granted July 19, 1904, to the Westinghouse Electric &Manufacturing Company on an application of N. W. Storer, sets forth amethod of control which consists in varying the voltage applied to themotor. by changing the connections of the battery from series tomultiple-groups, and the field magnet windings of the motor from seriesto'multiple sections. Patent No. 960,896, granted June 7 1910, to theBaker Motor Vehicle Company on an application of E. Gruenfeldt, setsforth a system of control in which a permanent circuit arrangementbetween the cells of the battery is maintained and the motor speed is,varied by changing the field magnet windings from a series to a multiplearrangement of sections and by the useof a variable resistance in thearmature circuit.

In a control system embodying a storage battery, it is considereddesirable, in most cases, to maintain a permanent connection andarrangement between the cells of the storage battery, but it is alsoparticularly I desirable, for automobile service, to secure a pluralityof motor speeds without dissipating energy by the use'of armatureresistance in any of the operating positions.

The aforesaid objective results are secured by the use of my invention,according to which the vehicle motor is provided with an armaturewinding having two relatively independent parts which are connectedeither in series or in multiple circuit rela-tion and a divided fieldmagnet winding,

the partsv which may also be connected in series or in multiple circuitrelation and combined with the various armature arrangements to producea plurality of eificient operating speeds from a constant potentialsource of energy.

One of the salient features of my invention is the method of changingfrom a series to a multiple relation between the parts of the armaturewinding without losing or varying the motor torque, and it' depends uponthe temporary shunting of one part of the motor armature winding and onepart of the field magnet winding by a resistor which is so designed asto permit the active half of the motor to. momentarily assume all of themotor load.

Figure 1 of the accompanying drawings 1s a diagrammatic view of a systemof control arranged and adapted to operate in accordance with myinvention. Figs. 2 to 9,

inclusive, are simple diagrams illustrating the relations between theparts of the motor armature winding and the sections of the motor fieldwindings. Fig. 10 is a diagrammatic plan view of a control drum and Fig.11 is a diagrammatic View embodying a single-plane development of thedevice shown in Fig. 10 and illustrating a modified arrangement forcarrying out my inventionwithout interrupting the motor circuit during acomplete adjustment of the controller. Figs. 12 to 29, inclusive, aresimple diagrams illustrating not only the arrangement and circuitconnections existing between the sections of armature winding and thefield magnet Winding of the motor, but also the arrangement andconnections of these members in the intermediate or transition positionsof the controller.

Referring to Figs. 1 to 9, inclusive, the system here shown comprises amotor 1 having an armature 2, commutators 3 and 4,

field magnet winding sections 5 and 6, a

storage battery 7, which may be replaced by any other source of energy,a resistor 8 and a controller 9 which is adapted to occupy a pluralityof forward positions a to e, inclusive, and reverse positions x, 11 andThe operation of the system is as follows: Assuming that the controller9 is in position a, circuit is established from a terminal 10 of thestorage battery 7 through conductor 11, contact fingers 12 and 13, whichare bridged by contact segment 14, conductor 15, commutator cylinder 3(circuit being completed through one section of the armature winding),conductor 16, contact fingers 17 and 18, which are bridged by contactsegment 19, conductor 20, commutator cylinder 4 (circuit being completedthrough the second section of the armature winding), conductor 21,contact fingers22 and 23, which are bridged by contact segment 24,resistor 8, section 5 of the field magnet winding, conductor 25, contactfingers 26 and 27, which are bridged by contact segment 28, conductor29, field magnet winding section 6 and conductor 30 to the oppositeterminal 31 of the battery 7. The circuit connections are thus completedthrough the two sections of the armature winding, the resistor 8 and thetwo sections of the field magnet. winding in series relation, as shownin Fig. 5. When the controller 9 is moved from position a to positionI), contact finger 32 moves into engagement with contact segment 24 andthus a shunt to the resistor 8 is completed from the contact finger 22.through contact segment 24, finger 32 and conductor 33 to section 5 ofthe field magnet winding. The circuit connections are now clearly shownin Fig. 6. As the controller successively occupies positions 0, d and e,the circuit connections shown in Figs. 7, 8 and 9 are effect.- ed, thesections of the field magnet winding being first connected in multiplecircuit relation with the armature sections in series, the armaturesections being then connected in multiple circuit relation with thefield sections in series and finally both the armature and the fieldmagnet winding sections being connected, in multiple circuit, the seriesrelation between the armature sections and the field sections beingmaintained.

Referring to Figs. 10 to 29, inclusive, the system here shown is similarto the system shown in Fig. 1, except that a controller 34 issubstituted for the controller 9. The controller 34 elfects the sameresults that are secured by the use of the controller 9 in each of themain positions of the controller, but a series of intermediatetransition positions are provided in order to secure such a successionof circuit changes ascto obtain the desired results without interruptingthe motor circuit or permitting any material reduction in the motortorque throughout the complete adjustment of the controller drum. Thisis particularly desirable for governing an electric driving motor of anautomobile or other road vehicle since it insures a particularly smoothacceleration of the motor. Most of the advantages, however, which can besecured by the controller of Figs. 10 and 11 are also secured by thecontroller of Fig. 1 which will usually be found preferable by reason ofits simplicity.

As controller 34 is moved from its off position to the position a, aresistor 35, corresponding to resistor 8 of Fig. 1, is temporarilyinserted and then short circuited, the circuit connections for thetransition position f being indicated in Fig. 12 and the connections forposition A being'indicated in Fig. 13. It will be observed that Fig. 13corresponds to Fig. 6. Passing from posi-. tion A to position B, thecontroller traverses two transition positions 9 and h, illustrated inFigs. 14 and 15, one section of the field magnet winding being firstshort circuited and then open circuited and finally connected'inparallel with the other section when the operating position B isreached. Between the position B and the operating position 0, eighttransition positions 2' to 27, inclusive, are located. The positions 5,]and 7c correspond, respectively, to the positions, h, g and A. In theposition 1, the resistor is connected in shunt circuit relation to onesection of the armature and one section of the. field magnet winding, asshown in Fig. 20. In position m, the shunted armature sections isdisconnected and in posi-. tion n, as shown in Fig. 22, it is connectedin multiple relation with the other armature section. In position 0,Fig. 23, one section of the field winding is short circuited and theresistor is connected in circuit. In position 79, Fig. 24, the fieldsection shunt is removed and finally, when the controller reachesposition C, the resistor is removed from the circuit. Between operatingpositions C and D, three transition positions q, 'r and 8 are locatedwhich difier from the preceding position as positions 9, h and B difi'erfrom the position (1. Finally, when the controller occupies position D,the mo tor is arranged in two parallel circuits, each including onesection of the armature winding and one section of the field magnetwinding.

Between the positions B and (Lone of the armature parts and one of thefield parts are short circuited by the resistor, as shown in Fig. 20,and under these conditions, the active half of the motor momentarilyassumes all of the motor load. This fact depends upon the magneticrelation between the two fields and between the two armature windingparts.

It is evident that variations may be effected in the circuit connectionsand in the proportioning of the controllers and their I variouspositions within the spirit and successively connecting the shuntedparts in multiple circuit relation with the corresponding active parts.

2. The method of controlling an electric motor having divided armatureand fieldmagnet windings which consists in connecting parts of thearmatureand parts of the field-magnet winding in series relation,shunting one armature and one field-magnet winding part by a translatingdevice, successively connecting the shunted parts in multiple relationwith the corresponding active parts and removing the translating devicefrom circuit intermediate the connecting of the respective shunted partsin multiple relation. i

Y 3'. The method of controlling an electric motor havin divided armatureand field magnet windings which consists in connecting parts of-thearmature and parts of the field magnet winding in series relation,shunting one armature and one field magnet winding part by a resistorand successively connectlng the shunted parts in multiple relation withthe corresponding active parts, whereby the entire motor load ismomentarily' borne by a part of the motor windings and the torque of themotor is maintained substantially constant.

4.. The method of controlling anelectric motor having divided armatureand field magnet windings which consists in connect ing parts of thearmature and parts of the fie d magnet winding in series relation,

doubling the current in certain parts of the windings by shunting aresistor across one armature and one field-magnet winding part,successively connecting the shunted parts in multiple relation with thecorresponding active parts and removing the resistor from circuitintermediate the connecting of the respective parts in multiplerelation, whereby the motor torque is maintained substantially constant.

5. The method of control which consists in connecting electric motorarmature windings and field magnet windings in series relation, shuntingone armature winding and one field magnet winding by a resistor,connecting the shunted armature winding in multiple circuit with theactive armature Winding, and finally connecting the shunted fieldwinding in multiple to the active field winding.

6. The method of controlling electric motors which consists inconnecting the armature windings and field magnet windings in seriescircuit relation, shunting one armature and one field magnet winding bya resistor, interrupting the circuit of said shunted windings,connecting the shunted armature winding in multiple relation with theother armature winding, connecting the shunted field winding in serieswith the other field winding, and removing the resistor from circuit.

7. The method of controlling electric motors which consists inconnecting the armature windings and field magnet windings in seriescircuit relation, shunting one armature and one field magnetwinding by aresistor, interrupting the circuit of said shunted windings, connectingthe shunted armature winding in multiple relation with the otherarmature winding, connecting the shunted field winding in series withthe other field winding, short circuiting one of the field windingsandconnecting it in series circuit with one of the armatures.

8. The method of controlling an electric motor having divided armatureand field magnet windings which consists in connect-..

ing parts of the armature and partsof the field magnet winding in seriescircuit relation, shunting one armature and one field magnet windingpart by a translatlng device, interrupting the circuit of said shuntedparts, and connecting parts of sa1d armature winding in multiplerelation and 1n series with one of the field magnet w ndmg parts and thetranslating device. v

In testimony whereof, I have hereunto subscribed my name this 31st dayof Oct., 1911.

JOSEPH LE CONTE DAVIS.

Witnesses:

J OHN S. DEAN, B. B. HINES.

